Abstract

A strong correlation between the Curie temperature and the metal–insulator transition is displayed in Ru doped where an equiatomic ratio of Ru and Mn is present in the Mn–O–Ru sublattice. The magnetic pair making effect of Mn with Ru is facilitated by the variable valency of Ru (IV)/Ru (V) which is similar in ionic size to the Zener pair Mn (III)/Mn (IV). Further Ru, being a metal with itinerant electrons, facilitates the exchange coupling interaction. The spin-wave excitation and the hole carrier density dominate the magnetization and the electron transport for for a higher Ru doped composition.